Recently the technologies of the liquid crystal displays have been advanced and improved quickly. Moreover, the production cost of the liquid crystal displays is continuously reduced. Therefore, the traditional cathode ray tubes (CRT) are almost completely replaced by the liquid crystal displays (LCD) in the market of the monitors. As the technologies of LCD are being improved greatly, the market of LCD TV is growing quite fast.
Although the LCD has plenty of advantage, e.g. the extremely thin in the dimension, large screen size, high resolution, etc, LCD still has a lot of performances required to be improved. Currently the light utilization rate of LCD is still very low, about less than 10%. That is, less than 10% of the light generated by the back light source finally reaches our eyes out of the LCD screen due to the technical characteristics of LCD. The reasons are explained briefly below.
Generally the white light is composed of three primary color lights, i.e. red, green and blue lights. Almost all the color light can be generated by mixing these primary color lights at the relatively various amounts. Currently almost all the color LCD utilizes the color filter to generate three primary color lights. However when the white light from the back light source passes through this color filter, only roughly one third (practically 30%) of light comes out, and the rest two third of light was absorbed by the red, green or blue pigment (or dye). On the other hand, polarizer inevitably used in LCD can only allow about 45% (50% in theoretically perfect condition) of light to pass through. Totally less than 10% of light at most can come out of the LCD screen after the light from the back light source passes the color filter and two polarizers.
Recently the issues of the environmental conservation and energy saving become more and more serious on the earth. It is extremely important to solve the problem of low light utilization rate in LCD caused by the color filter and the polarizer. It is noted that the color filter is the component with the lowest light utilization rate, about 30%, in LCD. Assuming, when the light utilization rate of the color filter is increased from 30% to 60%, then the total utilization rate of LCD will be increased from about 10% up to 20%, so the power consumption will be tremendously reduced to one half, 50%, of the original one. That is, a small amount in the improvement on the light utilization rate of the color filter will generate a significant amount in the total power saving.
In order to solve the above-mentioned problems, the new concept and the solution method are proposed in the present invention to raise the light utilization rate in LCD or other display devices. The present invention is described below.